Furnace apparatus

ABSTRACT

Shaft furnace apparatus comprising an upstanding furnace shell, and a supporting structure comprising a frame surrounding and spaced from the shell including generally horizontally disposed frame members joined end to end and being of substantial depth and having sides facing the shell, spaced legs supporting the frame, and a plurality of connector means fixed to such sides of the frame members and to the shell to support the shell from the frame, and means connected to the members forming the frame to resist tilting of the frame members about generally horizontal axes during expansion of the shell on heating of the furnace. Preferably, at least 25 percent of the weight of the furnace above the bosh portion is at all times supported by the supporting structure. If desired, the hearth portion of the furnace may be suspended below the frame and be essentially unsupported from below.

United States Patent 3,253,906 5/ 1966 Secord 266/25X 2,825,547 3/1958Vaughan (220/15UX) 3,129,836 4/1964 Frevel 220/1 Primary Examiner-J.Spencer Overholser Assistant Examiner.l0hn E. Roethel Att0rneyBosworth,Sessions, Herrstrom and Cain ABSTRACT: Shaft furnace apparatuscomprising an upstanding furnace shell, and a supporting structurecomprising a frame surrounding and spaced from the shell includinggenerally horizontally disposed frame members joined end to end andbeing of substantial depth and having sides facing the shell, spacedlegs supporting the frame, and a plurality of connector means fixed tosuch sides of the frame members and to the shell to support the shellfrom the frame, and means connected to the members forming the frame toresist tilting of the frame members about generally horizontal axesduring expansion of the shell on heating of the furnace. Preferably, atleast 25 percent of the weight of the furnace above the bosh portion isat all times supported by the supporting structure. If desired, thehearth portion of the furnace may be suspended below the frame and beessentially unsupported from below.

PATENTEU FEB 2:971

SHEET 3 OF 6 l N V L N T0 R S PATENI EU FEB 2191:

sum s or 6 Hmmkcm ATI'OP/l/EYJ FURNACE APPARATUS (ROSS REFERENCE. TORELATED APPLICATION This application is a division of applicantscopending appli cation Scr No, 520.945, filed .Ian. 17. Who Pat. No 3.43l ,fill

This invention relates to blast furnace structures and more particularlyto improved means for supporting blast furnaces.

In the United States, blast furnace structures heretofore conventionallyused generally have included a massive foundation set into the earth;the lower portion of the furnace including the hearth and bosh has beensupported by this foundation. lhe upper portion of the furnace,including the shaft and furnace top including the bells, distributor andupper portions of the downcomer, has been supported by a mantle that, inturn, has been supported on the foundation by numerous columnssurrounding the lower portion of the furnace in close proximity to eachother and to the lower portion of the furnace.

Such furnace structures have certain advantages in that the upper partof the furnace including the shaft and top supported by the mantle havebeen free to expand thermally as a unit on heating of the furnace. Thedowncomer attached to the furnace top also becomes heated duringoperation of the furnace, so it also expands and contracts with theportion of the furnace above the mantle, thus minimizing difficultiesthat might otherwise arise from thermal expansion.

However, in such furnace structures there have been substantialdifficulties arising from the differences in the thermal expansions ofthe supporting columns and the lower portion of the furnace below themantle. The mantle-supporting columns themselves are not subjected tosufficient heat to cause them to expand appreciably, but the lowerportion of the furnace is subjected to high temperature heat; therefore,the lower portion of the furnace tends to expand substantially onheating of the furnace until it bears substantially all of the weight ofthe furnace above the mantle and the apparatus supported by such portionof the furnace. On cooling, the lower portion of the furnace contractsand the entire load again is transferred to the columns. It, therefore,has necessarily been the practice to make the columns strong enough tosupport the upper portion of the furnace and apparatus supportedthereby, and also to make the lower portion of the furnace strong enoughto support the upper furnace portion and such apparatus; this hasinvolved substantial added costs. Furthermore, the lining of the furnacein the vicinity of the mantle has been susceptible to excessivedeterioration because of localized expansion and contraction arisingfrom transfer of the load from the columns to the lower portion of thefurnace and vice versa. The expansion joint often provided at thislocation to minimize this problem, itself has been a source of trouble.

In conventional European blast furnace structures, the lower portion ofthe furnace including the hearth and bosh, and the upper portion of thefurnace including the shaft but not the furnace top, are supported froma massive foundation set into the earth. The furnace top, including theloading equipment and downcomers, is supported from this foundation bylong posts or columns. This design tends to overcome the above describeddisadvantage of American-type structures, but introduces new problems.The bosh jacket is a structural element that supports the shaft of thefurnace; consequently, a hot spot in the bosh can impair the support forthe shaft; furthermore, the necessity for maintaining the bosh jacket asa structural supporting member increases the difficulties of reliningthe bosh. This design also makes it difficult to maintain a satisfactorytight joint between the furnace top and the portion of the furnace belowthe top, since the portion of the furnace below the top tends to expandon heating whereas the columns supporting the top do not expandappreciably if at all; this problem is accentuated when high toppressures are used according to modern practice. Other problems arisebecause the downcomer, supported from the columns, expands clue to heatwhile the columns themselves LII do not expand, and because a portion ofthe charge-distributing apparatus is usually supported by the furnacetop and moves as the furnace expands, and a portion is supported fromthe posts and does not move from thermal expansion, so jamming ofdistributor parts or gas leakage at the distributor may occur.

In conventional American furnace structures. as well as in most Europeanstructures. the columns or posts that support the upper portions of thefurnaces are so closely spaced in relation to the lower portions of thefurnaces, as well as to each other, that they impair access to the lowerportions of the furnaces for operations such as tapping, closing the tapholes and removing slag or spilled metal; they particularly impairaccess to these portions of the furnaces by automatic machinery forperforming these functions. Moreover, since the legs are closelydisposed relatively to the furnace, they can be damaged by molten metalin the event of breakouts. Furthermore, in both American and Europeanfurnace structure, it is very difficult, time-consuming and expensive toline the furnace, particularly the bosh and lower inwall portions whichmost frequently require lining, primarily because of the difficulties ofaccess to the furnace caused by the closely spaced columns and by theconstructions of the bosh and hearth portions which must act as supportsfor the upper furnace portions.

It is an object of the present invention to overcome as many of theseproblems and disadvantages as are desired. Another object is theprovision of a blast furnace structure in which the portion of thefurnace above the bosh, including the top, may be largely, or if desiredentirely, supported by legs or columns at all times during heating andcooling of the furnace. This minimizes or eliminates disadvantages ofAmerican-type furnace structures such as those arising out of transferof the support of the portion of the furnace above the mantle from thesupporting columns to the lower portion of the furnace and vice versa;and also eliminates the disadvantages of Europeantype furnace structuressuch as those arising from the necessity to maintain the bosh jacket asa support for the shaft, from the difficulty of sealing theindependently supported furnace top to the shaft. and from expansion ofthe downcomers and distributor parts relative to the nonexpandingsupporting posts supporting the furnace top,

A further object is the provision of a blast furnace structure in whichthe portions of the furnace above the mantle location, as well as thefurnace top if desired, are supported by widely spaced legs that permitgreatly increased access to the furnace for operations and use ofautomated equipment and repair or replacement of lining, and that reducepossibilities of damage to the legs in the event of breakouts of moltenmetal. Another object is the provision of a furnace structure of theabove type in which the hearth is suspended from the furnace shell andnot supported from below, so that the entire furnace is supported at alltimes from legs and both the upper portion and the lower portion of thefurnace can freely thermally ex pand and contract.

These and other objects of the invention will be apparent from thefollowing description of several embodiments of the invention inconnection with the accompanying drawings in which:

FIG. I is a perspective of a blast furnace structure embodying theinvention and having a suspended hearth portion, parts not pertinent tothe disclosure being omitted for clearness;

FIG. 2 is a vertical cross section, along line 2-2 of FIG. 1, partsbeing omitted for clearness;

FIG. 3 is a section along line 3-3 of FIG. 2 showing in plan the mainsupporting frame and lower centering means for the furnace, the scalebeing larger than in FIGS. 1 and 2; 1

FIG. 4 is an enlarged detail along line 4-4 of FIG. 1 showing one of themeans connecting the surrounding frame of the supporting structure tothe furnace shell;

FIG. 6 is a somewhat diagrammatic side elevation of the supportingstructure. illustrating prestressing and preforming of the supportingstructure before the load is applied.

Fl(i 7 is a vertical section to an enlarged scale of one of the supportsfor the legs.

HO. 8 is a section along line 8-8 of HG. 7.

FIG 9 is a detail of another embodiment of the invention in which thehearth is supported from the bottom but in which the remainder of thefurnace structure is essentially the same as in FIGS 1-8. parts beingomitted for clcarness'.

FIG. 10 is an enlarged detail. corresponding generally to H6. 4 in thelocation from which the section is taken. showing alternative means forconnecting the surrounding frame to the furnace of HO. 9 and alternativecooling means; and

HG. H is an enlarged detail. also corresponding generally to FIG. 4 inthe location of the section. of another embodi ment showing anothermeans for connecting the furnace to a surrounding supporting frame.

ln the furnace structure of FIGS. 1 to 8. inclusive. the furnace l issupported entirely free of the ground by supporting structure 2. Thefurnace 1 comprises shaft 3. bosh 4 and hearth portion 5. all enclosedin a continuous steel shell 6 free of sharp bends below its connectionto supporting structure 2 to provide adequate strength for the suspendedportion of the furnace. shell 6 comprises shaft shell portion 7. boshjacket 8 and hearth jacket 9. The furnace top is generally indicated as10.

The supporting structure 2 comprises a frame 12. surrounding and spacedfrom the furnace l in the vicinity of the ring 13. which is preferablylocated in essentially the same vertical relationship to furnace shaft 3as a mantle in a conventional furnace, Frame 12 is supported by fourlegs 14 from foundation members l set into the earth.

The furnace top of the illustrated structure is conventional andincludes a large bell hopper 16 containing a large hell (not shown). asuperposed rotatable distributor 17, the lower end of which is closed bya small hell (not shown). and a receiving hopper 18 above thedistributor into which burden or charge material is charged. All ofthese parts are supported by the furnace from the top of the furnaceshaft. Burden material may be conventionally charged into the receivinghopper by belts or skip cars traveling on a bridge (not shown).

Uptakes 21 are connected in conventional manner to the interior of thetop portion of the furnace, and discharge into a downcomer 22 connectedin the usual manner with a dust catcher. gas washer. stoves. etc.. notshown. These uptakes and the upper portion of the downcomer are alsosupported from the top of the shaft of furnace 1.

An auxiliary frame structure 23 is located above and rigidly supportedfrom supporting structure 2; it comprises upstanding legs 24 connectedto the supporting structure 2 and carrying a top working platform 25 anda lower working platform 26. the upper end of the skip or belt conveyorbridge. as well as superstructure 27 that supports the repair crane 28and other parts usually associated with the top of a furnace.

The furnace also includes conventional bustle pipe 29 surrounding thebosh. tuyeres 31. and associated cooling-water collecting trough 32. Aworking or cast house floor 33 at the lower end of the furnace carriesthe iron runners 34 extending away from the iron notches 35 and a slagrunner 36 extending away from the slag notch 37 in the furnace hearth.This floor is preferably supported independently of the legs 14 of thefurnace structure.

In the supporting structure 2. the frame 12 of the illustrated apparatusis made up of four deep steel beams 38 that are welded or bolted attheir ends to form a square in plan FIG. 3). Each of the illustratedbeams. which may be about l0 feet deep, is an l-section girder having awide vertical web or wall 39. top and bottom flanges 40 and 41. andreinforcing stiffeners 42 (FIG. 1); it may be coventionally fabricated.as by welding. from steel plates. The four legs [4 are rigidly connectedto frame 12 at the four corners thereof. as by welding or bolting.

At each of eight points of equal deflection on the frame 12. a connectormember 43 connects the adjacent l-beam 38 to the blast furnace shell 6in'the vicinity of the juncture of the shaft and bosh portions of thefurnace. preferably at a location such that when the furnace is empty orfilled the center of gravity of the furnace is below a horizontal planecontaining the center of gravity of the frame 12.

Each of these connector members 43. as shown in FlGS. l to 4. comprisesa flat member. preferably formed of thick steel plate. that extendsinwardly from the web 39 of the associated l-beam 38 of the frame 12 tothe shaft portion 7 of the furnace shell 6 and is rigidly fixed. as bywelding or bolting to both the l-beam and the furnace shell. Thesemembers 43 are essentially located in spaced vertical planes that extendessentially radially of the furnace shell and pass through and areequiangularly spaced about a vertical axis A" that is essentiallycoincident with the vertical axis of the furnace of supporting structure2. The lower portion of each member 43extends downwardly from the bottomof the l-beam 38 to a structural ring 13 located a substantial distancebelow the bottom. of beam 38 and fixed to the shell 6 of the furnace atthe juncture of shaft shell portion and the bosh jacket 8. Preferably.as shown in FIG. 4. a structural ring 45 is fixed to the shell 6 and theinner edge of each member 43. at a location on the shell below the topof frame 12; ring 45 is made of a radially-extending web 46 that iswelded or bolted to the shell and members 43. and a stiffening flange 47that is welded to the web. Rings 13 and45 are also laterally stiffenedby numerous reinforcing gussets 48a and 48b (FIGS. 1 and 4) welded tothe shell and the rings. if desired. each connector member 43 can bemade in two pieces 43a and 43b that are joined along line 50 tofacilitate erection. Upper piece 43a can be fixed to supporting frame12. and lower piece 43b can be attached to the furnace shell 6, afterwhich these parts of each member 43 can be welded together in the field.Members 49 are also fixed, as by welding, to the outer edges ofconnector members 43 and aid in reinforcing them.

A compression ring member 51. shown in the illustrated embodiment asoctagonal with sides of equal length and equal angles between the sides.is fixed. as by welding. to top flanges 40 of the l-beams 38 of the mainframe 12. and has intemallyextending projecting portions 52 that arewelded orotherwise rigidly fixed to the outer top edges of the connectormembers 43. This ring member 51 .resists tilting of the beams 38 abouttheir longitudinal generally horizontal axes. from the weight of thefurnace or from expansion of the furnace shell on heating. As thefurnace heats and its shell increases in diameter, the lower ends of theconnector members 43. which are deep enough so they themselves do notappreciably deflect. tend to move outwardly with the lower portion ofthe shaft shell portion 7 to which is affixed one generally verticaledge of each connector. This causes the upper ends of connectors 43 totend to move inwardly. which tends to cause the beams 38, to which arefixed the other spaced. generally vertical edges of connectors. to twistabout their longitudinal axes so their upper flanges 40 tend to movecloser to the furnace than their lower flanges 41. However, any tendencyof each l-beam thus to twist or tilt is resisted by the ring member 51that is thus subjected to compressive forces. Reinforcing members 49. oneach side of each connector member 43, also strengthen members 43against buckling. Since the ring member is a symmetrical polygon withstraight sides at the junctures of which the connectors are located. themember is exceptionally efficient in resisting the forces to which it issubjected.

There is a pair of divergent adjustable struts 53 connecting each of thefour sides of the frame 12 to the shell (FIG. 3). These struts areturnbuckle-types adjustable as to length. The struts of each pair arepivotally connected to widely spaced lugs 54 on the furnace shell 6essentially equidistant from the midpoint of the adjacent frame beam 38.and to lugs 55 on the web of such beam at locations closely adjacent toand essentially equidistant from its midpoint. preferably. nearer thetop of the beam than the bottom; these struts are generally tangentialto shell 6.

At the upper portion of the furnace pairs of divergent ad justablestruts 56 similar to struts 53. extend between the top of the furnaceshell and the auxiliary frame structure 23 (FIG 5 Struts 56 ofeach pairare pivotally connected to lugs 57 on the furnace shell 6 and to lugs 58on the adjacent girder 59 forming the top of the auxiliary frame 23,which is made strong enough to resist substantial lateral forces. Lugs57 and 58 for each pair of struts are located essentially equidistantlyfrom the center of the associated girder 59, below the top plat form 25,and each strut 56 is generally tangential to the furnace shell.

By suitable adjustments of the lengths of struts 53 and 56 it ispossible to cause them to center the furnace in the supporting structureformed of structure 2 and its attached auxiliary frame structure 23, toprevent twisting of the furnace in such structure. and to restrain thefurnace against lateral movement relative to such structure in the eventof seismic or other shocks, all without preventing vertical movements ofthe furnace or portions thereof relative to such structure as mightresult from thermal expansion or contraction. The furnace is thussupported at all times by a strong, stable supporting structure.

ln this embodiment. the shaft of the furnace is cooled by generallyhorizontal conventional cooling plates 60, extending transversely aroundthe circumference of the furnace in shaft inwall 61, through whichplates water is circulated by conventional means. The bosh may beconventionally cooled by water applied to its exterior.

The bottom portion 62 (FIGS. 1 and 2) of the hearth jacket 9 portion ofshell 6 preferably is essentially the shape of a hemiellipsoid having acircular cross section, and is lined with a suitable refractory materialsuch as a substantially uniformly thick layer 63 of carbon; the carbonlining in this embodiment continues upwardly at 64 throughout the hearthportion and the bosh up to the shaft inwall 61. The lower portion of thehearth is filled with refractory material, such as carbon or hightemperature refractory brick, to form a massive bottom 65. Thehemiellipsoidal shape of this portion of the hearth jacket is such thatdownwardly-acting forces on body 65, resulting from the weights of theliquid metal and the charge material resting on the metal, causesubstantially uniform outwardlydirected pressures on the portions 63 and64 of the lining and the portions of jacket 9 that enclose and supportthe body 65. THis hemiellipsoidal shape also minimizes distortion of thematerial of body 65 on heating and cooling.

Since the hearth portion of the furnace is suspended completely free ofany bottom support, numerous advantages result. The hearth portion canbe cooled more readily than in conventional furnaces because of thelarge additional cooling area of the exposed bottom. The vertical andhorizontal principal stresses in the hearth and bosh jackets are bothtension stresses, so that shear in the steel jackets and theirrefractory linings is low; this eliminates most if not all the prematurelining failure that occurs at these locations in conventional furnaces,in which the hearth and bosh support upper portions of the furnace, fromthe substantial shear developed in the jackets and lining materialbecause of large horizontal ring stresses. Moreover, the suspendedhearth portion facilitates repairing or replacing the lining of thefurnace, with considerable savings in labor and time, and considerablereduction in furnace downtime, because accessibility is considerablygreater than in conventional furnaces, and it is not necessary todismantle large amounts of auxiliary equipment at the lower portion ofthe furnace as is conventionally necessary. Thus, it is a relativelysimple matter to cut an opening in the wall of the furnace at floor 33and move in men and equipment, including highly automated equipment, forrelining purposes. The suspended design provides particularly importantadvantages in relining the lower inwall, bosh and hearth portions thatmost often require repair or replacement of lining. lt is also possibleto remove the entire lower hearth portion of the furnace, with the boshportion if desired, and replace it with a prefabricated linedreplacement portion by use of suitable jack-type dollies; it is merelynecessary to attach such replacement portion to the furnace and reline anarrow belt of refractory material at the joint.

Added advantages in strength and stability of support are provided if,before loading, the supporting structure 2 is prestressed and preformedto cause it to be formed and deflected prior to loading so that there islittle if any appreciable deflection visually apparent after the furnacestructure is completed. Preferably the legs 14 and also the beams 38 ofthe structure 2 are thus prestressed, and each beam 38 is built with acalculated camber when unloaded, so that each leg has no moment whensubjected to maximum loading, and so that each beam is essentially flatwhen subjected to maximum load- FIG. 6 shows diagrammatically the shapesof the beams 38 and legs 14 of a supporting structure 2 embodying theinvention when the structure 2 is prestressed but not loaded, and whenthe structure 2'is loaded with the weight of the furnace and otherstructure carried by the furnace. The full lines show, with greatexaggeration of curvature for the sake of clearness, the shape of thestructure 2 from its side when the legs 14, fabricated to have straightaxes, are prestressed and curved by having the lower ends of their outerlegs forced outwardly radially from the axis A of the structure 2 andthe furnace, to the positions they are calculated to assume under fullload. The beams 38 are also shown in full lines as cambered upwardlywhen the legs are prestressed. Although it might be expected that eachbeam would be deflected downwardly at its central portion because of theforces exerted on the ends of the beam by the rigid connections of thetops of the legs 14 to the beam ends, in the illustrated embodiment eachbeam 38 is fabricated so it has an upward cambered curve essentiallyidentical to the calculated deflection that will occur when the beam isloaded with its share of the weight of the furnace and other structuresupported by beams 38; therefore the prestressing of the legs 14 willdeflect the beam sufficiently to remove part, but not all, of the upwardcamber of beams 38. Beams 38 and legs 14 are preferably so designed, andthe prestressing of the legs is such, that after the structure is fullyloaded there is no visually appreciable deflection of the legs and beamsso that, as shown by broken lines of FIG. 6, the legs and the beams arestraight and can develop their maximum strength.

FIGS. 7 and 8 show means for moving the lower ends of the legs radiallyoutwardly to prestress them as described above, and to hold the ends insuch position while allowing the lower ends of said legs to rotatefreely, without subjecting the lower ends of the legs to bendingmoments. This means comprises a metal base member 66, fixed as bybolting to each foundation member 15 set into the earth; the uppersurface of this base member is normal to the axis B of the leg 14 whenthe leg is straight. An adjustable member 67 rests on member 66; it hasan upwardly-open annular groove 68, against the bottom and inner wall 69of which is fixed an annular bearing ring 71 of hardened metal providingan upwardly facing seat 72, spherical about point P. The outer wall 73of the groove 68 extends upwardly to provide a raised guard and guide.

The lower end of each leg 14 is tapered at 74 as shown and terminates ina casting 75 of thick cross section in which is fixed a seat 76 ofhardened metal and shaped to mate with spherical seat 72. Casting 75 hasa flange 77 that extends into the groove 68 adjacent outer wall 73;consequently the lower end of the leg 14 is prevented from movinglaterally off the seat 72 or jumping off the base in the event ofseismic shock or other large disturbances.

To draw the lower end of each leg outwardly to the desired prestressingposition, each member 67 is provided with two diametrically spaced lugs78, each connected by a drawbolt 79 to a lug 81 fixed to the base. Bytightening the nuts 82 on bolts 79 the desired amounts, each member 67supporting the bottom of a leg 14, can be moved from an initial positionshown in broken lines in FIG. 8 to its prestressing position shown infull lines in such figure without subjecting the leg to bending momentat its lower end, after which locking blocks 83 can be fixed. as bywelding. to the base member 66 to hold the lower end of the leg in thedesired prestressing position to provide the above described desirableresults The furnace of FIG. 9 includes a supporting structure 2 likethat of FIGS l3 including deep l-girders 38 joined at their ends to forma frame 12. that is square in plan configuration. that surrounds and isspaced from furnace 85, and that is supported from its corners by widelyspaced legs 14 that. as in the previous embodiment. are prestressedduring erection. This frame 12 is connected to the shell 86 of thefurnace by radially-extending equiangularly spaced connector members 43identical with. and fixed to the frame 12 and furnace shell by the samemeans as, connectors 43 of FIGS. 1-5. A compression ring member 51 andadjustable struts 53 at frame 12, and adjustable struts 56 are alsoprovided to connect the top portion of the furnace to girders 59 ofauxiliary frame structure 23. as in the previous embodiment. to performthe same or similar functions. in the embodiment of FIG. 9, however, thehearth portion 87 of the furnace is supported from beneath by afoundation 88 that is set into the earth. The hearth portion may beconventional in design. The remainder of the furnace structure of FIG. 9may be identical with that of FIGS. 15, inclusive. and like parts bearlike reference numerals. No further description is believed necessary.

FIG. shows to a larger scale alternative means for supporting furnace 85of FIG. 9 from supporting structure 2, and alternative cooling means.The furnace shell 89 in this case is conventional and includes a shaftshell portion 91 and a bosh jacket 92 joined at a mantle ring 93. Thesquare frame 12 of the furnace supporting structure 2 is identical withthat of FIGS. 1-4, being made of deep section I-girders 38 that areconnected together at their ends. This frame surrounds the furnace andis supported at the four corners by four legs 14, of which one is shownin FIG. 10. The frame is connected to the furnace shell by connectormembers 94 that, as in the previous embodiment, are equiangularlyradially disposed about the shell in essentially vertical planes. Theseconnectors are con nected to the beams 38 forming the frame 12 at pointsof equal deflection of the beams. Each connector member 94 is deep andstiff in a generally vertical direction, preferably formed of steelplate; it is fixed to the web 39 and the insides of the flanges 40 and41 of its associated I-beam 38, and to the furnace shell by being fixedto mantle 93, and to a radiallyprojecting lug or flange 95 fixed toshell 89 by a bolted joining strip 96. Stiffening lugs 97 are preferablyfixed to the mantle for added strength. A ring member 98, preferably ofequalsided, equiangular, octagonal plan shape like ring member 51 ofFIGS. l-4, is fixed to the top flanges 40 of the beams 38 forming framemember 12 in the same manner and location as ring member 51. A similarring member 99 is similarly fixed to and located on the bottom flanges41 of the beams 38.

The furnace of FIG. 10 also has generally horizontally-extendingconventional cooling plates 101 in the bosh section, through whichplates water is circulated by conventional means. The shaft of thefurnace is cooled by hollow cooling staves 102, 103, formed of iron orother suitable metal and extending transversely along the circumferenceof the furnace in the inwall 104; water is circulated through the stavesby conventional means. The upper staves 102 are conventional in thatthey are of rectangular cross section; the lower staves 103 differ inthat the upper portion 105 of each stave is considerably wider than itslower portion 106; preferably its exterior top width is about twice itsexterior bottom width. This stave shape causes the load resulting fromthe weight of the brick work or other material forming the inwall 104 ofthe shaft to be carried down into the reentrant corner between the shaftshell portion 91 and the inwardly-extending portion of mantle 93; thisoccurs because the material forming the inwall bears on theinwardly-projecting wider upper portions of these lowermost staves tourge these staves downwardly into such comer to distribute the loadthrough the lining material located outwardly of these staves, to themantle and adjacent portion of the shell.

The design of FIG 10 permits independent assembly of the supportingstructure 2 and connector members 94. independent assembly of the shell89, and subsequent joining of the connector members 94 to the shell bystrips 96. In this embodiment. moreover. the ring members 98 and 99 atthe tops and bottoms of beams 38 of the frame 12 resist tilting of thebeams from the weight of the furnace or thermal expansion or contractionof the furnace shell on heating or cooling of the furnace. The remainderof the furnace structure illustrated by FIG. 10 may be like that of FIG.9.

In the modification of FIG, 11 shown as applied to the furnace of FIG 9,the furnace'85 comprising shell 107 is supported from a supportingstructure 2 identical with that of FIGS. 1-4, comprising a frame 12 thatis supported by legs, not shown, like the widely spaced legs 14 of theprevious embodiment. As in the previous embodiment. four deep I-girders38 are joined aT their ends to define a frame 12 that is square in plan.At points of equal deflection on the frame 12 and equiangularly spacedaround the furnace shell there are radially-extending deep, stiff,generally vertical connector members 108 formed of steel plate that arefixed to the webs 39 of the beams 38 of frame 12, as by welding orbolting, and that are rigidly connected to the furnace shell above themantle by connector strips 109 bolted to members 108 and toradiallyextending lugs 111 fixed to the shell.

In the supporting structure, there is a ring member 112 which preferablyis identical to member 51 of FIGS. l- -4, inclusive, and to member 98 ofFIG. 9 in that it is of equal-sided, equiangular octagonal shape inplan, fixed to the tops of upper flanges 40 of the beams of the frame12. Another preferably identical ring member 113 is similarly fixed toand located on the undersides of the bottom flanges 41 of the beams 38.

In this embodiment, conventional generally horizontally-extendingcooling plates 114 are provided, through which cooling water iscirculated in the usual manner.

The ring members 112 and 113 stabilize the frame 2 and the furnace shellin the same manner as do corresponding members in the structure of FIG.6 by preventing harmful tilting of beams 38 of frame 12. Preferably.adjustable struts are provided, of the type and location of struts 53and 56 of the embodiment of FIGS. l5, to perform the same functions. Theremainder of the apparatus, not shown, may be identical with theapparatus of FIG. 9. l

The furnace structures illustrated in each of FIGS. 9, 10 and 11 providemany of the advantages indicated above in connection with the furnacestructure of FIGS. 1-8 as arising from improved accessibility to thelower portion of the furnace because of the widely spaced legs, althoughit does not provide the advantages arising from the suspended hearth,such as rapid replacement of the suspended hearth as a whole, unimpededdownward expansion, and increased cooling area. However, in thestructures of FIGS. 9 to 11, the supporting structure 2 formed of theframe 12 and the legs 14 can be designed to be stiff enough to supportthe load of the furnace above the connector members connecting the frame12 to the furnace shell, but limber enough so that if the portion of thefurnace below the connectors contracts on cooling, the supportingstructure can permit sufficient downward movement of the upper portionof the furnace to permit the lower and upper portions of the fumace wallin the vicinity of the'mantle to remain an essentially continuous wall,and thus eliminate the necessity for an expansion joint that is oftenlocated near the mantle in conventional furnaces, which expansion jointis often a source of trouble. i

In the embodiment of FIGS. 1 to 8, the entire weight of the furnace andstructure supported by the furnace is supported by structure 2. This,therefore, completely avoids the previously discussed problems arisingin conventional American and European furnaces because the portions ofthe furnace above the bosh must be supported by the hearth and boshportions, since in this embodiment the hearth and bosh are notsupporting elements.

In each of the embodiments of FIGS. 9 to II. inclusive, supportingstructure 2 is so designed that at least about 25 percent. andpreferably 50 percent or even more, of the weight of the furnace abovethe connections of the fumace above the bosh to frame I2 is at all timescarried by the supporting structure 2. even when the furnace is hot andthe hearth and bosh portions lengthen to positions where otherwise theywould support the portion of the furnace above the bosh. Therefore. thehearth and bosh portions need not be designed to carry as much weight asin conventional American or European blast furnaces. and thissubstantially minimizes and can eliminate most if not all of theproblems described above as arising in conventional furnaces because thehearth and bosh portions must support essentially all of the weight ofthe furnace and apparatus above the bosh.

Preferablyv in each of the previously described embodiments, the legs 14of the supporting structure 2 are hollow and are filled with pouredconcrete introduced by conventional apparatus and methods throughopenings 120 (FIGS. 3, 4 and in the upper ends of the legs 14.Preferably the concrete 121 extends essentially from the bottom of eachleg as shown in FIG. 7 to the upper end of each leg as shown in FIGS. 4and 10, to insure that when hardened the concrete extends throughout atleast the portion of each leg that is subject to deflection. If desired,as shown in FIGS. 7 and 8, reinforcing steel I22 may be embedded in theconcrete I21. Preferably the concrete is of the type that does notshrink, or that may even expand slightly, on curing to insure permanentfirm contact of the concrete with the inner walls of the legs Maximumbenefits are provided when the hollow legs 14, while empty of concrete.are, prior to loading of supporting structure 2, first prestressed byhaving their lower ends moved outwardly from their initial unstressedposition in a direction and by an amount essentially corresponding tothe direction and amount that the lower end of each leg would moveoutwardly from its unstressed position if the supporting structure 2 ofwhich the leg forms a part was subjected to a load corresponding to thefurnace, so that the legs are deflected as indicated by the full linesin FIG. 6, the lower ends of the legs being then locked in suchpositions; structure 2 is then loaded with the furnace so the legs 14assume positions in which they are essentially undeflected as shown inbroken lines in FIG. 6 and in full lines in FIGS. 1, 2 and 9 in whichthe legs are shown straight; and the legs are thereafter filled withpoured concrete which is then allowed to solidify.

The concrete. after it has hardened and cured, stiffens the legs 14 andacts to maintain them in their undeflected conditions, in which theyhave their maximum strength. This is particularly important since theframe structure as initially designed has deep, stiff cross beams 38 andlegs 14 which, while strong enough to support the load of the furnaceeven before the addition of the concrete, are relatively limber sincethey are made of steel and capable of being deflected in theprestressing operation. Addition and curing of the concrete while thelegs are in their straight or undeflected positions increases thestiffness of the legs and their resistance toward bending.

The concrete in the legs also adds substantial mass to the legs whichare of relatively large cross section and considerable length; forexample, if the legs are circular in cross section they may be as muchas 5 feet or even more in diameter for a furnace of modern largecapacity. This large added mass and the resistance of the concrete tocompressive forces provides added protection against damage from impactson the legs, such as might occur from a derailed railroad car, thusadding to the safety of the furnace structure. The added mass of theconcrete also acts to substantially absorb and dissipate the energy ofeither steady or transient vibrations to which the legs 14 or thefurnace structure as a whole may be subjected, thus damping outvibrations which could otherwise be harmful. Steady vibrations couldoccur from operation of sifting machinery or unbalanced equipment whichcould cause undesirable resonance; transient vibrations could occur fromseismic shocks or passing railroad rolling stock. The damping action ofthe large mass of concrete in each leg prevents undesirable resonance orharm from such vibrations.

The concrete in each leg can also act as a high capacity heat sink thatcan absorb and transmit away from a point of localized exposure on theleg heat from hot metal. slag or coke that might approach or contact thelegs in the event of a furnace breakout. The concrete thus providesadded protection for the legs in this respect.

The above advantages of the concrete filling are provided if the legsare of circular cross section as shown. or of other hollow crosssections including polygonal cross sections such as a square crosssection.

It is apparent that various modifications can be made in any of thefurnace structures illustrated. For example. the furnace tops inFIGS. 1. 2 and 9 could be supported from the auxiliary supportingstructure 23, instead of from the top of the furnace shaft, althoughwhen the top is supported on the furnace as in the illustratedembodiments advantages arise because the top can move upwardly anddownwardly as the furnace shaft expands and contracts. The connectormeans of FIGS. 10 and I1 could be used in the structure of FIGS. 1-8, aswell as in the structure of FIG. 9.

While four legs of circular cross section are shown, one each corner ofa four-sided supporting frame, supporting frames of different shapes,preferably polygonal, supported by a different number of legs may beused, and the legs may be of circular or other, even polygonal, crosssection. In any event the number and cross section of the legs should besuch that adequate support and stability are provided. It appears thatfor most, if not all. uses four legs and a square-sided supporting frameare most advantageous from the standpoint of stability, adequatesupport, economy and cost. The legs in the illustrated embodiment arediagonally inclined, for increased stability of the furnace structure;however, they may be vertically disposed, if desired.

Other modifications will be apparent to those skilled in the art. It isintended that the patent shall cover, by suitable expression in theappended claims, whatever features of patentable novelty reside in theinvention.

We claim:

1. Shaft furnace apparatus comprising a furnace shall having upstandingsidewall means, and a supporting structure for the furnace comprising aframe surrounding and spaced from said shell and said sidewall means andincluding generally horizontally disposed frame member means ofsubstantial depth and having a side facing said shell, spaced legssupporting said frame, a plurality of connector means fixed to said sideof said frame member means and to said upstanding sidewall means of saidshell and extending through the space between said frame and said shellto support said shell from said frame, and means connected to said frameand not affixed to said shell to resist tilting of said frame membermeans about generally horizontal axes thereof.

2. The apparatus of claim I in which said connector means are fixed tosaid frame member means at locations of essentially equal deflection onsaid frame member means.

3. The apparatus of claim 1 in which said connector means extendessentially radially of said shell and are disposed essentiallyequiangularly around said shell.

4. The apparatus of claim 1 in which said means connected to said frameto resist tilting of said frame member means comprises ring means fixedto the upper portions of said frame member means above the locations atwhich said connector means are fixed to said frame member means.

5. The apparatus of claim 1 in which said means connected to said framemember means to resist tilting of said frame comprises first ring meansfixed to the upper portion of said frame member means above thelocations at which said connector means are fixed to said frame membermeans, and second ring means fixed to the lower portion of said framemember means below the locations at which said connector means are fixedto said frame member means.

6. The apparatus of claim 1 comprising members adjustable as to lengthconnecting said furnace shell to said frame to assist in centering saidshell relative to said frame.

7. The apparatus of claim 1 in which said connector means are fixed tosaid shell to support said furnace aboyc its center of gravity.

8. The apparatus of claim I in which the lower portions of saidconnector means where they are fixed to said frame are above the lowerportions of said connector means where they are fixed to said shellsidewall means 9. The apparatus of claim 1 in which said supportingstructure constitutes essentially the only support for said furnace andthe lower end of said furnace is suspended from said supportingstructure and unsupported from below.

10. THe apparatus of claim 9 in which the bottom of said furnace isessentially hemiellipsoidal.

H. The apparatus of claim 1 in which at least 25 percent of the weightof the furnace above the locations at which said connector means arefixed to said furnace shell is at all times supported by said supportingstructure.

12. The apparatus of claim 1 in which said frame is formed of four beamseach having a generally vertical wall of substantial depth, said beamsbeing joined to form a frame that in plan is of essentially squareconfiguration and that surrounds and is spaced from said shell. in whichapparatus said legs support said frame at the corners of said frame, andin which apparatus said connector means comprises generally verticalmembers fixed to and extending essentially radially of said shell andfixed to said walls of said beams at points of essentially equaldeflection of said beams.

13. The apparatus of claim 12 in which said means resisting tilting ofsaid frame members comprises a ring member fixed to the upper portionsof said walls of said beams.

14. The apparatus of claim 12 in which said means to resist tilting ofsaid frame members comprises a ring member fixed to the upper portionsof said walls of said beams and another ring member fixed to the lowerportions of said walls of said beams.

15. Shaft furnace apparatus comprising a furnace having a hearth portionand a shell having a sidewall portion and a lower portion that enclosessaid hearth portion; supporting structure for the furnace comprising agenerally horizontally disposed frame surrounding and spaced asubstantial distance from said sidewall portion of said shell entirelyaround said shell, legs supporting said frame and spaced from saidfurnace and from each other, said legs being diagonally inclinedrelative to said furnace at substantial angles from the vertical withthe bottoms of said legs spaced outwardly a substantial distance fromthe tops of said legs to provide substantial stability for said frameand said furnace, means spaced around said shell and connected to saidsidewall portion of said shell and to said frame and extending betweensaid frame and said shell for supporting said furnace from said frame sothe hearth portion of said furnace is suspended below said frame and isessentially unsupported from below and so said spaced means supportingsaid furnace from said frame are connected to said sidewall portion ofsaid furnace shell above the center of gravity of said furnace, andmeans, independent of said means for supporting said furnace from saidframe, connected to said furnace and said frame for restraining saidfurnace against lateral movement relative to said frame.

16. The apparatus of claim 15 in which the bottom of said furnace isessentially hemiellipsoidal.

17. The apparatus of claim 15 in which the sidewall of the shell isessentially free of sharp bends that could substantially impair thestrength of said sidewall for suspending the suspended portions of saidfurnace.

18. Apparatus of claim I in which said means connected to said frame toresist tilting of said frame member means com prises ring means that ispolygonal in plan with straight side membersjoincd at the locations ofessentially equal deflection on said frame member means. v

19. Apparatus of claim 2 in which said means connected to said frame toresist tilting of said frame member means comprises ring means that ispolygonal in plan with straight side membersjoined at the locationsofessentially equal deflection on said frame member means.

20. Shaft furnace apparatus comprising an upwardly extending furnace,supporting structure for said furnace comprising an essentially rigidgenerally horizontally disposed frame surrounding and spaced from saidfurnace, means supporting said furnace from said frame, and meanslocated between said frame and said furnace for restraining said furnaceagainst lateral, movement relative to said supporting structurecomprising tension members connected to said furnace and said frame andextending generally tangentially to said furnace.

21. The furnace of claim 20 in which said tension members are adjustableas to length.

22. Shaft furnace apparatus comprising an upwardly extending furnace,supporting structure for said furnace comprising an essentially rigidgenerally horizontally disposed frame surrounding and spaced from saidfurnace, said frame being made up of a plurality of beam members thatare essentially equal in length and rigidly connected together to definein a plan a symmetrical polygon means supporting said furnace from saidframe, and means located between said frame and said furnace forrestraining said furnace against lateral movement relative to saidsupporting structure, saidrestraining means comprising two elongatedmembers connected to each of said beam members and to said furnace shelland extending tangentially to said shell in generally .oppositedirections.

23. Shaft furnace apparatus comprising an upwardly extending furnace,supporting structure for said furnace comprising an essentially rigidgenerally horizontally disposed frame surrounding and spaced from saidfumace,said frame being made up of four members of generally equallength to form a frame that is essentially square in plan configuration,means supporting said furnace from said frame, and means located betweensaid frame and said furnace for restraining said furnace against lateralmovement relative to said supporting structure, said restraining meanscomprising tension members connected to said furnace shell and to eachof said frame members at essentially the central portion thereof.

24. Shaft fumace'apparatus comprising an upwardly extending furnace,supporting structure for said furnace comprising an essentially rigidgenerally horizontally disposed frame surrounding and spaced from saidfurnace, means supporting said furnace'from said frame, means locatedbetween said frame and said furnace for restraining said furnace againstlateral movement relative to said supporting structure, essentiallyrigid upper supporting structure surrounding and spaced from saidfurnace and extending from said first-mentioned supporting structureupwardly adjacent the upper portion of said furnace, and means locatedbetween said furnace and said upper supporting structure for restrainingsaid furnace against lateral movement relative to said upper supportingstructure comprising tensionmembers connected to said upper supportingstructure and said furnace and extending generally tangentially to saidfurnace.

25. The apparatus of claim 24 in which said tension members areadjustable as to length.

1. Shaft furnace apparatus comprising a furnace shall having upstandingsidewall means, and a supporting structure for the furnace comprising aframe surrounding and spaced from said shell and said sidewall means andincluding generally horizontally disposed frame member means ofsubstantial depth and having a side facing said shell, spaced legssupporting said frame, a plurality of connector means fixed to said sideof said frame member means and to said upstanding sidewall means of saidshell and extending through the space between said frame and said shellto support said shell from said frame, and means connected to said frameand not affixed to said shell to resist tilting of said frame membermeans about generally horizontal axes thereof.
 2. The apparatus of claim1 in which said connector means are fixed to said frame member means atlocations of essentially equal deflection on said frame member means. 3.The apparatus of claim 1 in which said connector means extendessentially radially of said shell and are disposed essentiallyequiangularly around said shell.
 4. The apparatus of claim 1 in whichsaid means connected to said frame to resist tilting of said framemember means comprises ring means fixed to the upper portions of saidframe member means above the locations at which said connector means arefixed to said frame member means.
 5. The apparatus of claim 1 in whichsaid means connected to said frame member means to resist tilting ofsaid frame comprises first ring means fixed to the upper portion of saidframe member means above the locations at which said connector means arefixed to said frame member means, and second ring means fixed to thelower portion of said frame member means below the locations at whichsaid connector means are fixed to said frame member means.
 6. Theapparatus of claim 1 comprising members adjustable as to lengthconnecting said furnace shell to said frame to assist in centering saidshell relative to said frame.
 7. The apparatus of claim 1 in which saidconnector means are fixed to said shell to support said furnace aboveits center of gravity.
 8. The apparatus of claim 1 in which the lowerportions of said connector means where they are fixed to said frame areabove the lower portions of said connector means where they are fixed tosaid shell sidewall means.
 9. The apparatus of claim 1 in which saidsupporting structure constitutes essentially the only support for saidfurnace and the lower end of said furnace is suspended from saidsupporting structure and unsupported from below.
 10. THe apparatus ofclaim 9 in which the bottom of said furnace is essentiallyhemiellipsoidal.
 11. The apparatus of claim 1 in which at least 25percent of the weight of the furnace above the locations at which saidconnector means are fixed to said furnace shell is at all timessupported by said supporting structure.
 12. The apparatus of claim 1 inwhich said frame is formed of four beams each having a generallyvertical wall of substantial depth, said beams being joined to form aframe that in plan is of essentially square configuration and thatsurrounds and is spaced from said shell, in which apparatus said legssupport said frame at the corners of said frame, and in which apparatussaid connector means comprises generally vertical members fixed to andextending essentially radially of said shell and fixed to said walls ofsaid beams at points of essentially equal deflection of said beams. 13.The apparatus of claim 12 in which said means resisting tilting of saidframe members comprises a ring member fixed to the upper portions ofsaid walls of said beams.
 14. The apparatus of claim 12 in which saidmeans to resist tilting of said frame members comprises a ring memberfixed to the upper portions of said walls of said beams and another ringmember fixed to the lower portions of said walls of said beams. 15.Shaft furnace apparatus comprising a furnace having a hearth portion anda shell having a sidewall portion and a lower portion that encloses saidhearth portion; supporting structure for the furnace comprising agenerally horizontally disposed frame surrounding and spaced asubstantial distance from said sidewall portion of said shell entirelyaround said shell, legs supporting said frame and spaced from saidfurnace and from each other, said legs being diagonally inclinedrelative to said furnace at substantial angles from the vertical withthe bottoms of said legs spaced outwardly a substantial distance fromthe tops of said legs to provide substantial stability for said frameand said furnace, means spaced around said shell and connected to saidsidewall portion of said shell and to said frame and extending betweensaid frame and said shell for supporting said furnace from said frame sothe hearth portion of said furnace is suspended below said frame and isessentially unsupported from below and so said spaced means supportingsaid furnace from said frame are connected to said sidewall portion ofsaid furnace shell above the center of gravity of said furnace, andmeans, independent of said means for supporting said furnace from saidframe, connected to said furnace and said frame for restraining saidfurnace against lateral movement relative to said frame.
 16. Theapparatus of claim 15 in which the bottom of said furnace is essentiallyhemiellipsoidal.
 17. The apparatus of claim 15 in which the sidewall ofthe shell Is essentially free of sharp bends that could substantiallyimpair the strength of said sidewall for suspending the suspendedportions of said furnace.
 18. Apparatus of claim 1 in which said meansconnected to said frame to resist tilting of said frame member meanscomprises ring means that is polygonal in plan with straight sidemembers joined at the locations of essentially equal deflection on saidframe member means.
 19. Apparatus of claim 2 in which said meansconnected to said frame to resist tilting of said frame member meanscomprises ring means that is polygonal in plan with straight sidemembers joined at the locations of essentially equal deflection on saidframe member means.
 20. Shaft furnace apparatus comprising an upwardlyextending furnace, supporting structure for said furnace comprising anessentially rigid generally horizontally disposed frame surrounding andspaced from said furnace, means supporting said furnace from said frame,and means located between said frame and said furnace for restrainingsaid furnace against lateral movement relative to said supportingstructure comprising tension members connected to said furnace and saidframe and extending generally tangentially to said furnace.
 21. Thefurnace of claim 20 in which said tension members are adjustable as tolength.
 22. Shaft furnace apparatus comprising an upwardly extendingfurnace, supporting structure for said furnace comprising an essentiallyrigid generally horizontally disposed frame surrounding and spaced fromsaid furnace, said frame being made up of a plurality of beam membersthat are essentially equal in length and rigidly connected together todefine in a plan a symmetrical polygon means supporting said furnacefrom said frame, and means located between said frame and said furnacefor restraining said furnace against lateral movement relative to saidsupporting structure, said restraining means comprising two elongatedmembers connected to each of said beam members and to said furnace shelland extending tangentially to said shell in generally oppositedirections.
 23. Shaft furnace apparatus comprising an upwardly extendingfurnace, supporting structure for said furnace comprising an essentiallyrigid generally horizontally disposed frame surrounding and spaced fromsaid furnace, said frame being made up of four members of generallyequal length to form a frame that is essentially square in planconfiguration, means supporting said furnace from said frame, and meanslocated between said frame and said furnace for restraining said furnaceagainst lateral movement relative to said supporting structure, saidrestraining means comprising tension members connected to said furnaceshell and to each of said frame members at essentially the centralportion thereof.
 24. Shaft furnace apparatus comprising an upwardlyextending furnace, supporting structure for said furnace comprising anessentially rigid generally horizontally disposed frame surrounding andspaced from said furnace, means supporting said furnace from said frame,means located between said frame and said furnace for restraining saidfurnace against lateral movement relative to said supporting structure,essentially rigid upper supporting structure surrounding and spaced fromsaid furnace and extending from said first-mentioned supportingstructure upwardly adjacent the upper portion of said furnace, and meanslocated between said furnace and said upper supporting structure forrestraining said furnace against lateral movement relative to said uppersupporting structure comprising tension members connected to said uppersupporting structure and said furnace and extending generallytangentially to said furnace.
 25. The apparatus of claim 24 in whichsaid tension members are adjustable as to length.